A chamber used in baking that encourages fermentation of dough by yeast through warm temperatures and controlled humidity. One who proofs. quotations ▼ A printer used to make proofing copies that look like how it will come out of the press.A proofer (aka proofing oven, proofing cabinet, dough proofer, proofing drawer, or proof box) is a warm area (70-115°F) designed to maximize proofing by keeping dough warm and humid. You can DIY a proofing box by placing a loaf pan at the bottom of the oven and pouring 3 cups boiling water into the pan.